IEEE 802.16 is an emerging suite of standards for Broadband Wireless Access (BWA) commonly known as WiMAX. WiMAX is one of the wireless technologies targeting the fourth generation of wireless mobile systems. The IEEE 802.16e amendment to the IEEE 802.16 base specification enables combined, fixed, and mobile operation in licensed and license-exempted frequency bands under 11 GHz. IEEE 802.16 defines a high-throughput packet data network radio interface capable of supporting several classes of Internet Protocol (IP) applications and services including isochronous applications such as Voice Over IP (VoIP) and applications with burst data access profiles such as Transfer Control Protocol (TCP) applications. The standards defined in IEEE 802.16-2004 and IEEE 802.16-2005 are both hereby incorporated by reference.
The basic WiMAX network coverage is provided using an approach similar to other mobile wireless technologies (e.g., using high power macro base stations). In order to increase the intra-cell coverage and capacity, distributed small base station entities have been considered. Depending on the number of target users and the type of applications envisioned, these small base station entities have been defined by the WiMAX industry as nano, pico or femto base stations. Relay stations (RS) have also been introduced to extend radio coverage or to increase the throughput of a macro base station (MBS). An RS, which transfers data of active service flows between an MBS and mobile stations (MS), may be a low-cost alternative to an MBS.
The femto base station (fBS) is the smallest base station entity. An fBS is, in essence, a small WiMAX MBS that a user can purchase and install in his home or office. It basically provides the user's MS the same air interface function as an MBS based on the IEEE 802.16 standard. Compared to a MBS, the fBS is a low-cost, low-power radio system having reduced capabilities. The users can put the FBS in their building to boost bandwidth and coverage area and enable new applications such as fixed/mobile convergence. Being located in the user's building, the fBS often provides higher signal strength and better link quality than the MS would get from the MBS outside the user's building.
The fBS is envisioned as being installed at the customer's premise by the customer with little or no support from the network operator. This is different than other types of small base station entities, which are typically installed and commissioned by the network operator. Since fBSs are operated in a home or office environment, it is natural to consider fBSs as private equipment which is only accessible by the owners' devices. However, in certain situations the owners of fBSs may provide service to the MSs of non-owners. Such fBSs may be referred to as public accessible fBSs.